Hello, I just planted 2 Spireas about 3 weeks ago, I followed directions to plant them. I've been watering them regularly. It's been hot and dry in southern Michigan. The outer leaves and stems are green and the flowers are in bloom, but I noticed last night the inner stems and leaves are brown and dried up. Any help? I called the nursary where I purchased them, I do have a 1 yr warranty and they recommend fertilizer. Also said they may recover. Thanks!